Ogygis Undae
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Ogygis Undae is the only named southern hemisphere dune field on Mars.[1] It is named after one of the classical albedo features on Mars, Ogygis Regio.[2] Its name, which refers to Ogyges, a primeval mythological ruler in ancient Greece,[2] was officially approved by the International Astronomical Union (IAU) on September 17, 2015. It is situated just outside Argyre Planitia, a plain located in the southern highlands of Mars.[3] The dunes of Ogygis Undae extend from latitude −49.94°N to −49.37°N and from longitude 292.64°E to 294.93°E (65.07°W – 67.36°W).[2] They are centered at latitude −49.66°N, longitude 293.79°E (66.21°W), and extend approximately 87 km to the east and west from there.[4][2] Ogygis Undae has an area of 1904 km2, and due to its large size is a primary subject for research on Martian dune morphology and sand composition.[4][3]
Ogygis Undae is the final sink of an extended sand transport system that was imaged with the HRSC camera onboard ESA Mars Express. The complexity of this transport system is as extensive as some terrestrial examples. Dunes in Ogygis Undae have several morphologies including: barhcan, barchanoid, dome and star dunes. The variety of dune types indicates that they were deposited in a multimodal wind regime with different winds converging into the basin where the dunes are located, carrying sand from multiple source areas.[4] The morphological complexity is mirrored by the diverse mineral composition of the dune-forming sediment.[3]
